System and method for improved pressure adjustment

The present invention relates to a system and method for adjusting the pressure in an inflatable object. More particularly, the present invention relates to a system and method for adjusting the pressure in an air bed in less time and with greater accuracy.

Advances made in the quality of air beds having air chambers as support bases have resulted in vastly increased popularity and sales of such air beds. These air beds are advantageous in that they have an electronic control panel which allows a user to select a desired inflation setting for optimal comfort and to change the inflation setting at any time, thereby providing changes in the firmness of the bed.

Air bed systems, such as the one described in U.S. Pat. No. 5,904,172 which is incorporated herein by reference in its entirety, generally allow a user to select a desired pressure for each air chamber within the mattress. Upon selecting the desired pressure, a signal is sent to a pump and valve assembly in order to inflate or deflate the air bladders as necessary in order to achieve approximately the desired pressure within the air bladders.

In one embodiment of an air bed system, there are two separate air hoses coupled to each of the air bladders. A first air hose extends between the interior of the air bladder and the valve assembly associated with the pump. This first air hose fluidly couples the pump to the air bladder, and is structured to allow air to be added or removed from the air bladder. A second hose extends from the air bladder to a pressure transducer, which continuously monitors the pressure within the air bladder. Thus, as air is being added or removed from the air bladder, the pressure transducer coupled to the second hose is able to continuously check the actual air bladder pressure, which may then be compared to the desired air pressure in order to determine when the desired air pressure within the bladder has been reached.

In another embodiment of an air bed system, there is only a single hose coupled to each of the air bladders. In particular, the hose extends between the interior of the air bladder and the valve assembly associated with the pump, and is structured to allow air to be added or removed from the air bladder. Instead of having a second hose with a pressure transducer coupled thereto for continuously reading the pressure within the air bladder, a pressure transducer is positioned within a chamber of the valve assembly. Once the user selects the desired air pressure within the air bladder, the pressure transducer first senses a pressure in the chamber, which it equates to an actual pressure in the air bladder. Then, air is added or removed from the bladder as necessary based upon feedback from the sensed pressure. After a first iteration of sensing the pressure and adding or removing air, the pump turns off and the pressure within the chamber is once again sensed by the pressure transducer and compared to the desired air pressure. The process of adding or removing air, turning off the pump, and sensing pressure within the chamber is repeated for several more iterations until the pressure sensed within the chamber is within an acceptable range close to the desired pressure. As one skilled in the art will appreciate, numerous iterations of inflating and deflating the air bladder may be required until the sensed chamber pressure falls within the acceptable range of the desired pressure.

Thus, while this second embodiment of an air bed system may be desired because it minimizes the necessary number of hoses, it is rather inefficient in that numerous iterations may be required before the sensed pressure reaches the desired pressure. Furthermore, the pump must be turned off each time the pressure transducer takes a pressure measurement, which increases the amount of time that the user must wait until the air bladder reaches the desired pressure.

Therefore, there is a need for an improved pressure adjustment system and method for an air bed that is able to minimize the amount of time and the number of adjustment iterations necessary to achieve a desired pressure in an air bladder, while also increasing the accuracy of the actual bladder pressure.

The present invention solves the foregoing problems by providing a method for adjusting pressure within an air bed comprising providing an air bed that includes an air chamber and a pump having a pump housing, selecting a desired pressure setpoint for the air chamber, calculating a pressure target, adjusting pressure within the air chamber until a pressure within the pump housing is substantially equal to the pressure target, determining an actual chamber pressure within the air chamber, and comparing the actual chamber pressure to the desired pressure setpoint to determine an adjustment factor error. The pressure target may be calculated based upon the desired pressure setpoint and a pressure adjustment factor. Furthermore, the pressure adjustment factor may be modified based upon the adjustment factor error determined by comparing the actual chamber pressure to the desired pressure setpoint.

The present invention also provides a pressure adjustment system for an air bed comprising an air chamber, a pump in fluid communication with the air chamber and including a pump manifold and at least one valve, an input device adapted to receive a desired pressure setpoint selected by a user, a pressure sensing means adapted to monitor pressure within the pump manifold, and a control device operably connected to the input device and to the pressure sensing means. The control device includes control logic that is capable of calculating a manifold pressure target based upon the desired pressure setpoint and a pressure adjustment factor, monitoring pressure within the pump manifold, adjusting pressure within the air chamber until the sensed manifold pressure is within an acceptable pressure target error range of the manifold pressure target, comparing an actual chamber pressure to the desired pressure setpoint to quantify an adjustment factor error, and calculating an updated pressure adjustment factor based upon the adjustment factor error.

Referring now to the figures, and first to, there is shown a diagrammatic representation of air bed systemof the present invention. The systemincludes bed, which generally comprises at least one air chambersurrounded by a resilient, preferably foam, borderand encapsulated by bed ticking.

As illustrated in, bedis a two chamber design having a first air chamberA and a second air chamberB. ChambersA andB are in fluid communication with pump. Pumpis in electrical communication with a manual, hand-held remote controlvia control box. Remote controlmay be either “wired” or “wireless.” Control boxoperates pumpto cause increases and decreases in the fluid pressure of chambersA andB based upon commands input by a user through remote control. Remote controlincludes display, output selecting means, pressure increase button, and pressure decrease button. Output selecting meansallows the user to switch the pump output between first and second chambersA andB, thus enabling control of multiple chambers with a single remote control unit. Alternatively, separate remote control units may be provided for each chamber. Pressure increase and decrease buttonsandallow a user to increase or decrease the pressure, respectively, in the chamber selected with output selecting means. As those skilled in the art will appreciate, adjusting the pressure within the selected chamber causes a corresponding adjustment to the firmness of the chamber.

shows a block diagram detailing the data communication between the various components of system. Beginning with control box, it can be seen that control boxcomprises power supply, at least one microprocessor, memory, at least one switching means, and at least one analog to digital (A/D) converter. Switching meansmay be, for example, a relay or a solid state switch.

Pumpis preferably in two-way communication with control box. Also in two-way communication with control boxis hand-held remote control. Pumpincludes motor, pump manifold, relief valve, first control valveA, second control valveB, and pressure transducer, and is fluidly connected with left chamberA and right chamberB via first tubeA and second tubeB, respectively. First and second control valvesA andB are controllable by switching means, and are structured to regulate the flow of fluid between pumpand first and second chambersA andB, respectively.

In operation, power supplyreceives power, preferably 110 VAC power, from an external source and converts it to the various forms required by the different components. Microprocessoris used to control various logic sequences of the present invention. Examples of such sequences are illustrated in, which will be discussed in detail below.

The embodiment of systemshown incontemplates two chambersA andB and a single pump. Alternatively, in the case of a bed with two chambers, it is envisioned that a second pump may be incorporated into the system such that a separate pump is associated with each chamber. Separate pumps would allow each chamber to be inflated or deflated independently and simultaneously. Additionally, a second pressure transducer may also be incorporated into the system such that a separate pressure transducer is associated with each chamber.

In the event that microprocessorsends a decrease pressure command to one of the chambers, switching meansis used to convert the low voltage command signals sent by microprocessorto higher operating voltages sufficient to operate relief valveof pump. Alternatively, switching meanscould be located within pump. Opening relief valveallows air to escape from first and second chambersA andB through air tubesA andB. During deflation, pressure transducersends pressure readings to microprocessorvia A/D converter. A/D converterreceives analog information from pressure transducerand converts that information to digital information useable by microprocessor.

In the event that microprocessorsends an increase pressure command, pump motormay be energized, sending air to the designated chamber through air tubeA orB via the corresponding valveA orB. While air is being delivered to the designated chamber in order to increase the firmness of the chamber, pressure transducersenses pressure within pump manifold. Again, pressure transducersends pressure readings to microprocessorvia A/D converter. Microprocessoruses the information received from A/D converterto determine the difference between the actual pressure in the chamberand the desired pressure. Microprocessorsends the digital signal to remote controlto update displayon the remote control in order to convey the pressure information to the user.

Generally speaking, during an inflation or deflation process, the pressure sensed within pump manifoldprovides an approximation of the pressure within the chamber. However, when it is necessary to obtain an accurate approximation of the chamber pressure, other methods must be used.

One method of obtaining a pump manifold pressure reading that is substantially equivalent to the actual pressure within a chamber is to turn off the pump, allow the pressure within the chamber and the pump manifold to equalize, and then sense the pressure within the pump manifold with a pressure transducer. Thus, providing a sufficient amount of time to allow the pressures within the pump manifoldand the chamber to equalize may result in pressure readings that are accurate approximations of the actual pressure within the chamber. One obvious drawback to this type of method is the need to turn off the pump prior to obtaining the pump manifold pressure reading.

A second method of obtaining a pump manifold pressure reading that is substantially equivalent to the actual pressure within a chamber is through use of the pressure adjustment method in accordance with the present invention. The pressure adjustment method is described in detail in. However, in general, the method functions by approximating the chamber pressure based upon a mathematical relationship between the chamber pressure and the pressure measured within the pump manifold (during both an inflation cycle and a deflation cycle), thereby eliminating the need to turn off the pump in order to obtain a substantially accurate approximation of the chamber pressure. As a result, a desired pressure setpoint within a chamber may be achieved faster, with greater accuracy, and without the need for turning the pump off to allow the pressures to equalize.

is a circuit diagram modelof the air bed systemillustrated in. As shown in, first and second chambersA andB may be modeled by capacitorsA andB, motorof pumpmay be modeled by current sourceand resistor, relief valvemay be modeled by resistor, pressure transducermay be modeled by resistorand a voltage sensing lead, first and second tubesA andB may be modeled by resistorsA andB, and first and second valvesA andB may be modeled by resistorsA andB. Additionally, pump manifoldmay be modeled by another capacitorbecause it also acts as a chamber, albeit much smaller than first and second chambersA andB.

As those skilled in the art will appreciate, by assuming current sourceis a constant current source, pressure readings may be analogized with voltage readings. Thus, in reference to the circuit diagramin, the voltages associated with capacitorsA andB may be used to analyze pressure within first and second chambersA andB, respectively. Because the voltage readings are not dependent upon the capacitance value of capacitorsA andB, the capacitance value may be discarded for purposes of the present analysis. Translated to pressure terms, this means that the size of first and second chambersA andB is irrelevant when measuring the pressure within the chambers.

Furthermore, weight positioned on a chamber (such as that caused by the user lying on bed) is directly related to the volume of the chamber and does not affect the ability of the system to measure the pressure within the chamber. In addition, because the system measures pressure in real time, weight changes do not affect the ability of the control system to accurately measure chamber pressure.

The relationship between the voltage on first or second capacitorsA orB and the voltage sensed at voltage sensing leadis dependent upon whether current is flowing toward the capacitor (i.e., the chamber is going through an inflation cycle) or away from the capacitor (i.e., the chamber is going through a deflation cycle). In particular, and as will be discussed in detail with reference to, modeling air bed systemas circuit diagramresults in an additive manifold pressure offset factor during an inflation cycle and a multiplicative manifold pressure factor during a deflation cycle.

The relationship between voltage associated with a chamber capacitor (i.e., the “chamber voltage”) and the sensed “manifold” voltage during an inflation cycle may be stated as follows:Chamber Voltage=(Manifold Voltage)−(Inflate Factor)  (Eq. 1)

Restated in terms of pressure, the relationship between the pressure within a chamber and a sensed manifold pressure during an inflation cycle may be stated as follows:Chamber Pressure=(Manifold Pressure)−(Inflate Factor)  (Eq. 2)

In one exemplary embodiment, the inflate offset factor may generally fall in a range between about 0.0201 and about 0.1601. Because pressure readings may be analogous to voltage readings as discussed previously, the value of the inflate offset factor will be the same regardless of whether the relationship between the chamber and the pump manifold is being stated in terms of pressure or voltage.

The relationship between voltage associated with a chamber capacitor and the sensed manifold voltage during a deflation cycle may be stated as follows:Chamber Voltage=(Manifold Voltage)×(Deflate Factor)  (Eq. 3)

Restated in terms of pressure, the relationship between the pressure within a chamber and a sensed manifold pressure during a deflation cycle may be stated as follows:Chamber Pressure=(Manifold Pressure)×(Deflate Factor)  (Eq. 4)

In one exemplary embodiment, the deflate factor may generally fall in a range between about 1.6 and about 6.5. Once again, because pressure readings may be analogous to voltage readings as discussed previously, the value of the deflate factor will be the same regardless of whether the relationship between the chamber and the pump manifold is being stated in terms of pressure or voltage.

is an exemplary graphillustrating the pressure relationships derived from circuit diagramofand discussed in detail above. In particular, the vertical axis on the graph represents pressure in pounds per square inch (psi), while the horizontal axis on the graph represents time in milliseconds (ms). Thus, the graph illustrates a measure of chamber pressure over time.

In particular, a first portionof the graphbetween about 0 ms and about 65000 ms represents the inflation of a chamber from about 0 psi to about 0.6 psi. A second portionof the graphbetween about 65000 ms and about 135000 ms represents the pressure in the chamber being maintained at about 0.6 psi. Finally, a third portionof the graphbetween about 135000 ms and about 200000 ms represents deflation of the chamber from about 0.6 psi to about 0 psi.

With further reference to the graph in, the solid linerepresents the actual pressure within the chamber throughout the inflation and deflation cycles, while broken linerepresents the sensed pump manifold pressure throughout the inflation and deflation cycles. As illustrated in, in the first portionof the graphrepresenting inflation of the chamber, linesandare generally linear and offset from one another by a substantially constant additive offset factor. In this exemplary graph, the additive inflate offset factor is about 0.0505. Thus, the pressure within the chamber may be approximated during an inflation cycle by subtracting from the sensed manifold pressure an inflate offset factor of about 0.0505. Linesandgenerally converge in the second portionof the graphwhen the chamber is being neither inflated nor deflated. Finally, in the third portionof the graphrepresenting deflation of the chamber, linesandare both non-linear and offset from one another by a substantially constant multiplicative factor. In this exemplary graph, the multiplicative deflate factor is about 2.25. Thus, the pressure within the chamber may be approximated during a deflation cycle by multiplying the sensed manifold pressure by a deflate factor of about 2.25.

Now that a brief description of an air bed system and the relationship between chamber and pump manifold pressures have been provided, one embodiment of an improved pressure adjustment method according to the present invention will be described in detail. For purposes of discussion only, the pressure adjustment method in accordance with the present invention will be described in reference to first chamberA. However, those skilled in the art will appreciate that the pressure adjustment method applies in a similar manner to other chambers, such as second chamberB of bed.

In particular,illustrates a flowchart of a sample control logic sequence of a pressure setpoint monitoring methodaccording to the present invention. The sequence begins at stepupon the occurrence of a “power-on” event. A power-on event may be, for example, coupling power supplyof control boxto an external power source. The sequence continues at stepwhere microprocessorobtains one or more default adjustment constants stored in, for example, memory. In one exemplary embodiment, these default adjustments correspond with the additive inflate factor and the multiplicative deflate factor previously described. Thus, for instance, the default additive inflate factor may be about 0.0505, while the default multiplicative deflate factor may be about 2.25. Workers skilled in the art will appreciate that these default values are approximate and were determined for the particular air bed system modeled inabove with an average sized user, and that these values may change as modifications are made to the air bed system. These default adjustment constants will be used by the improved pressure adjustment method of the present invention until they are later updated after a first pressure adjustment iteration as will be discussed in further detail to follow.

The sequence continues at stepwhere microprocessordetects whether a new pressure setpoint has been selected by the user to either increase or decrease the pressure in first chamberA. The new pressure setpoint may be a pressure that is either higher or lower than the current pressure in first chamberA, as desired by the user. As will be appreciated by those skilled in the art, the range of possible chamber pressures is not important to the operation of the present invention. Thus, numerous pressure ranges are contemplated. The new pressure setpoint may be selected by, for example, manipulating pressure increase buttonor pressure decrease buttonon manual remote control. Alternatively, the pressure increase and decrease buttons may be provided on another component of system, such as pump.

If microprocessordoes not detect that a new pressure setpoint has been selected, the sequence then continues at stepwhere microprocessordetermines whether or not there has been an interfering event, such as a loss in power. If microprocessordetermines that a loss in power has occurred, the adjustment factors are then discarded in stepand the sequence loops back to stepto monitor for the occurrence of another power-on event. However, if microprocessordetermines that a loss in power has not occurred, the sequence enters monitoring loopwhere microprocessorcontinually monitors whether a new pressure setpoint is selected in stepor whether a loss in power has occurred in step.

Alternatively, if microprocessordetects that a new pressure setpoint has been selected in step, then the sequence continues to pressure adjustment methodas will be described in detail in reference to. Thus, the selection of a new pressure setpoint by the user triggers a pressure adjustment.

As will be appreciated by those skilled in the art, air bed system may include a back-up power source such that if the power to power supplyis interrupted, the pressure adjustment factors remain stored within memory. As a result, it may be possible to avoid the discarding step previously described.

illustrates a flowchart of a sample control logic sequence of an exemplary pressure adjustment methodaccording to the present invention. The sequence begins at stepwhen pressure transducersamples the pressure within pump manifold. Because motorof pumpis not running at this point, air is neither flowing into or out of first chamberA. Therefore, the manifold pressure sampled in stepis substantially stable and a fairly accurate approximation of the actual pressure within first chamberA. After the manifold pressure has been sampled in step, the method continues at stepwhere microprocessorcompares the sampled manifold pressure to the desired pressure previously selected by the user (in step) to determine if an adjustment is required. In one embodiment, microprocessorcalculates the difference between the sampled manifold pressure and the desired pressure setpoint selected by the user, and compares the difference to a predetermined, acceptable “error.” The acceptable error may be any value greater than or equal to zero. If the absolute value of the difference between the sampled manifold pressure and the desired pressure setpoint selected by the user is less than or equal to the acceptable error, then no adjustment is required, and the pressure adjustment method ends at stepwhere microprocessordetermines that the pressure adjustment process is complete. However, if the difference between the sampled manifold pressure and the desired pressure setpoint selected by the user is not within the acceptable error range, then an adjustment is required, and the pressure adjustment method continues at step.

In step, microprocessordetermines if inflation or deflation of first chamberA is required. If it is determined in stepthat deflation of first chamberA is required, the method continues at stepwhere microprocessorcalculates a deflate pressure target, which corresponds to the sensed manifold pressure that will yield the desired pressure setpoint during a deflation cycle. In particular, the deflate pressure target may be calculated through use of Equation 4 above. Based upon the relationship between chamber pressure and manifold pressure during a deflation cycle recited in Equation 4, the deflate pressure target may calculate as follows:Deflate Manifold Pressure Target=(Desired Pressure Setpoint)/(Deflate Factor)

The first time the user selects a new pressure setpoint that requires deflation of first chamberA, the deflate factor will be set to the default value of 2.25 discussed above in step. However, as will be discussed in further detail to follow, this deflate factor will be modified at a later step in order to more accurately reflect the mathematical relationship between the chamber pressure and the sensed manifold pressure for that particular user.

Once the deflate pressure target is calculated in step, microprocessorinstructs pumpto begin the deflate operation in step.

Alternatively, if it is determined in stepthat inflation of first chamberA is required, the method continues at stepwhere microprocessorcalculates an inflate pressure target. The inflate pressure target corresponds to the sensed manifold pressure that will yield the desired pressure setpoint during an inflation cycle. In particular, the inflate pressure target may be calculated through use of Equation 2 above. Based upon the relationship between chamber pressure and manifold pressure during an inflation cycle recited in Equation 2, the inflate pressure target may calculate as follows:Inflate Manifold Pressure Target=(Desired Pressure Setpoint)+(Inflate Offset Factor)

The first time the user selects a new pressure setpoint that requires inflation of first chamberA, the inflate factor will be set to the default value of 0.0505 discussed above in step. However, as will be discussed in further detail to follow, this inflate factor will be modified at a later step in order to more accurately reflect the mathematical relationship between the chamber pressure and the sensed manifold pressure for that particular user.

Once the inflate pressure target is calculated in step, microprocessorinstructs pumpto begin the inflate operation in step.

After performing the pressure deflate operation in stepor the pressure inflate operation in stepas required, the manifold pressure within pump manifoldis once again sampled in step. Because either motorof pumphas been running in order to inflate first chamberA, or relief valvehas been open in order to deflate first chamberA, the manifold pressure sampled in stepis now instable and by itself does not provide an accurate representation of the actual pressure within first chamberA. However, because of the known relationship between manifold pressure and chamber pressure discussed previously, the present invention is able to accurately approximate the actual chamber pressure based upon a sensed manifold pressure. Therefore, after the manifold pressure has once again been sampled, the method continues at stepwhere microprocessorcompares the sampled manifold pressure to the manifold pressure target calculated in either stepor stepto determine if the manifold pressure target has been achieved.

Similar to the process utilized in step, microprocessorcalculates the difference between the sampled manifold pressure and the manifold pressure target and compares the difference to a predetermined, pressure target error. The pressure target error may be any value greater than or equal to zero. If the absolute value of the difference between the sampled manifold pressure and the manifold pressure target is greater than the acceptable pressure target error, then further inflation or deflation is required. As a result, pressure adjustment methodreturns along pathto either deflate operationor inflate operation, depending upon whether the manifold pressure sampled in stepwas less than or greater than the manifold pressure target. On the other hand, if the difference between the sampled manifold pressure and the manifold pressure target is within the pressure target error limit, then no further inflation or deflation is necessary, and the pressure adjustment method continues at stepwhere the inflate or deflate operation is ended.

Next, pressure transduceronce again samples the pressure within pump manifoldat step. Because all inflate or deflate operations have ceased, air is neither flowing into nor out of first chamberA, and the manifold pressure sampled in stepis substantially stable and a fairly accurate approximation of the actual pressure within first chamberA. After the manifold pressure has been sampled again in step, the sequence continues at stepwhere microprocessorcompares the “actual” manifold pressure sampled in stepwith the “expected” user setpoint pressure previously selected by the user (in step) to determine if the desired setpoint pressure has been achieved. If the actual manifold pressure sampled in stepis not substantially equal to the expected setpoint pressure selected by the user, then an adjustment must be made to the pressure adjustment factor. An updated adjustment factor is therefore determined based upon a comparison between the sensed pressure and the desired setpoint pressure, and the pressure adjustment factor is thereafter modified in step.

With regard to the deflate pressure adjustment factor, an updated factor may be calculated in the following manner:Updated Deflate Adjustment Factor=(Pressure Setpoint from Step)/(Manifold Pressure from Step)